User's Guide

LE920A4 HW User Guide Hardware Commands
Doc#: 1VV0301261 Turning on the Module
Rev. 4.7.1 Page 46 of 124 2019-11-21
5. Hardware Commands
Turning on the Module
To turn on the module, the ON/OFF pad must be asserted low for at least 1 second and
then released.
The maximum current that can be drained from the ON/OFF pad is 0.1 mA. This pin is
internally pulled up; customers should expect to see ~ 800 mV on the output.
Figure 3 illustrates a simple circuit to power on the module using an inverted buffer output.
Figure 3: Power-on Circuit
Initialization and Activation State
After turning on the module, the module is not yet activated because the SW initialization
process of the module is still in process internally. It takes some time to fully complete the
HW and SW initialization of the module.
For this reason, it is impossible to access the module during the Initialization state.
As shown in Figure 4, the module becomes operational (in the Activation state) at least 20
seconds after the assertion of ON_OFF.
NOTE:
During the Initialization state, AT commands are not available. The DTE host
must wait for the Activation state prior to communicating with the module.